Traditionally, when a voltage source providing a direct current (DC) voltage is connected to a battery-powered electronics system, a charger or a battery management circuit uses the DC voltage to charge the battery. Additionally, a power management unit (PMU) uses the DC voltage to power the applications in the system. On the other hand, when the DC voltage is not connected to the system, the battery supplies the voltage and powers the applications. These approaches generally use both a battery management circuit and a power management unit (PMU) to manage the power, e.g., to decide when to take the power from the battery and when to take the power from the DC voltage source. Usually, the battery management circuit and the PMU are two separate units built on complementary chips. Efficient power regulation and reduced form factor are two key parameters to mobile electronics system design.
In a power management system (PMS) known to the applicant, both the battery management circuit and the PMU use switching DC-DC architectures to improve efficiency and minimize power loss. A switching DC-DC architecture typically employs a power inductor. The cost of building the charger and the PMU using discrete power inductors continues to be expensive, because the cost of discrete inductors has not decreased significantly even though the cost of the silicon to build the integrated circuit has dropped in many situations, the cost of discrete inductors almost exceeds the cost of the total silicon. Integrating the power inductors into the semiconductor fabrication and assembly process is cumbersome and cost inhibitive.
Like reference symbols in the various drawings indicate like elements.